The invention relates to a barbed tape and a process for forming a barbed tape wherein the barbs of the tape are stiffened against bending.
Barbed tape is widely used as an anti-personnel barrier in numerous private and government applications such as prison facilities, military installations, and the securing of private residences and the like. Such tape typically includes an elongated generally flat central support structure having clusters of barbs at spaced apart locations. Each cluster of barbs typically comprises a first pair of barbs extending from a root on one edge of the tape and a second pair of barbs extending from a root on the opposite edge of the tape. Each barb is a generally elongated planar structure having two generally opposed edges converging toward one another and meeting at a very sharp point. The barbs in each pair lie in a common plane, with points extending in generally opposite directions relative to one another.
The above described barbed tape is formed into a helical configuration such that the plane of the tape is aligned generally perpendicular to the axis of the helix. Thus, the points of the barbs extend in generally tangential directions relative to the helix, while the roots to which the pairs of barbs are joined extend generally in radially outward and inward directions relative to the helix.
Such a helical configuration of tape may be arranged along the tops of walls or barriers or at ground level so as to serve as a barrier to intruders.
Helical coils of barbed tape are deployed such that a person attempting to pass therethrough will contact at least a portion of the tape. This initial contact often will be with one or more of the closely spaced barbs on the tape, which are formed with sufficient sharpness to inflict a severe wound. This initial contact with the tape will also cause wavelike movements elsewhere in the helical tape causing other barbed clusters to be urged into contact with the intruder. Thus, even if the initial contact with the helical barbed tape is at a location spaced from a barbed cluster, this initial harmless contact is likely to urge other barbed clusters into the intruder.
One problem frequently encountered with the foregoing is that the barbs must be made of a relatively thick material to provide sufficient rigidity so that they do not merely bend rather than inflict the intended injury. However, such thick material results in added expense, provides a barb which is less sharp, and accelerates wear to stamping and die cutting machines used to make such tape.
U.S. Pat. No. 4,718,641 to Mainiero discloses a barbed tape wherein the barbs are reinforced with flanges, or stepped or embossed portions or the like. Such reinforcement provides the barbs with some degree of resistance to bending. However, the non-embossed portions of the barbs are still relatively susceptible to bending.
It is of course desirable to provide a barbed tape wherein the tape is made from a thin material so as to save on material costs, provide a sharper point to the barbs, and reduce wear on stamping and die cutting equipment and the like used for forming the tape, while barbs of the tape remain sufficiently resistant to bending.
It is therefore the principal object of the present invention to provide a barbed tape and a process for forming same wherein at least a substantial portion of the barb is stiffened, strengthened and/or work hardened so that a thinner material can be utilized to prepare the tape so as to provide a sharp barb while maintaining the desired rigidity or resistance to bending of the barb.
It is another object of the invention to provide a process for forming such a barbed tape wherein the use of a thinner material reduces wear on stamping and die cutting machinery and also reduces the overall material cost of the tape.
Other objects and advantages will appear hereinbelow.